bcma: Fix typo in comments

Remove the repeated word "registers" in comments.

Signed-off-by: Shaomin Deng <dengshaomin@cdjrlc.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220811152043.11446-1-dengshaomin@cdjrlc.com